Why does Pakistan always lose to India?

Answer :- 

Pakistan always looses !!! Really ??
Lets see the head to head record of encounters between two countries.
  1. ODIs
    1. Total maches played =  127
    2. Pakistan victories =  72
    3. Indian victories = 51
    4. No result/Draw = 4
  2. Test matches
    1. Total maches played =  59
    2. Pakistan victories =  12
    3. Indian victories = 9
    4. No result/Draw = 38
  3. T20s
    1. Total maches played =  7
    2. Pakistan victories =  1
    3. Indian victories = 5
    4. No result/Draw = 1

It is clearly visible that in terms of victories Pakistan is ahead of India in both Test cricket and ODI cricket. Its the T20s where they are currently running behind.
It is actually the cricket world cups where Pakistan is never able to beat India. Looking the world cup encounters between these countries, one can easily deduce that it is Indian teams ability of handling the pressure, which has brought them world cup victories against Pakistan. On the other hand Pakistan has always spoiled the winning chances in world cup matched.

Records point towards a dominant Pakistan when it comes to Ind-Pak games.
However, over the last decade or so, the momentum seems to be shifting. The Indian cricket team relies on multi-dimensional players who get more global exposure and analytical support than their neighbors.
Despite playing less cricket, Pakistan manages to put up a fight almost every time. In about 10 years, if the political situation in Pak stabilizes, the two sides will easily be the best in the world. As it is, sub-continent nations dominate world cricket.
Coming back to your query, there is no definite answer as to why Pakistan has been losing consistently in recent times. Maybe it's a lean patch for the team against their most preferred as well challenging rivals.

source:- quora.com